Experts have uncovered further evidence that a chromosomal test can boost the chances of success with IVF.

Chromosomal abnormalities can cause embryos to fail, even though they may look healthy under a microscope.

Array comparative genomic hybridisation (CGH) enables scientists to analyse chromosomes and transfer only the healthiest embryos, increasing the chance of a successful pregnancy.

Dozens of babies have now been born in the UK as a result of the technique, which was pioneered in the UK and is available at several clinics.

In the latest study, published in the journal Fertilisation In Vitro, experts analysed data for 134 couples undergoing 150 cycles of array CGH.

The women were older, typically aged 41, and couples had a history of miscarriage or failed IVF.

The results showed a live birth rate of 24.1% per embryo transfer in patients undergoing array CGH, compared to 16.7% and 12.5% in groups where the test was not used.

National IVF figures put the live birth rate for women aged 40 to 42 at under 13%, suggesting the test could almost double this rate.

The latest study was carried out by experts at Care Fertility clinics in Nottingham and Manchester.

Professor Simon Fishel, lead author on the paper and managing director of Care Fertility, said the live birth rate was impressive given the fact the women were older and many had suffered long-term infertility or repeated miscarriages.

Chromosomal abnormalities are a major cause of miscarriage and the chance of abnormality increases significantly with a woman's age.

He said the technique, which costs around £2,400 on top of usual IVF costs, could also help younger women who may be unable to get pregnant due to problems with their eggs.

"What we can't do is keep doing the same thing over and over and expecting a different result," he said.

"Some clinics do keep putting patients through repeated IVF cycles when they could actually benefit from this test.

"I think this is a paradigm shift and it will get better and better as the skills for using this technology keep improving."

The tests were carried out on women's eggs but Care is also now working on embryos.

Prof Fishel added: "We know that chromosome abnormality is a major cause of miscarriage and IVF failure.

"Our team at Care have studied 150 cases, the largest study undertaken worldwide, and concluded that using this technique dramatically increases the chance of implantation.

"All couples undergoing IVF could benefit from this test which can reliably detect faulty chromosomes prior to implantation.

"Array CGH is a not only a triumph of UK ingenuity but also a real insight into the viability of an embryo."

Dagan Wells, from Oxford University, who is developing a new test combining chromosomal screening with other markers that can cause embryos to fail, welcomed the new research.

He said: "This is good work using a method developed in the UK, which is now widely used around the world.

"The method provides patients with useful information about the number of healthy eggs they produce. Unfortunately, some will learn that they don't produce any viable eggs.

"This is a disappointing result, but is still very valuable as it lets them know that IVF is unlikely to work for them, potentially saving them from the heartache, stress and expense of undergoing multiple unsuccessful treatments.

"Applying chromosome screening to eggs may provide a small improvement in pregnancy, as well as reducing the risks of miscarriage and Down's syndrome, but it is important not to over-hype the benefits.

"Research suggests that much bigger improvements are seen when embryos are screened, rather than eggs."